Surpassing MySQL's TIME value limit of 838:59:59

I'd just retrieve the total number of seconds worked, and convert to hours/minutes as required in the presentation layer of my application (it is, after all, a simple case of division by 60):

<?
  $dbh = new PDO("mysql:dbname=$dbname", $username, $password);
  $dbh->setAttribute(PDO::ATTR_EMULATE_PREPARES, FALSE);

  $qry = $dbh->prepare('
    SELECT SUM(TIME_TO_SEC(entry_end_time)-TIME_TO_SEC(entry_start_time))
    FROM   entry 
    WHERE  entry_date BETWEEN :start_date AND :end_date
       AND user_id = :user_id
  ');

  $qry->execute([
    ':start_date' => '2012-01-01',
    ':end_date'   => '2012-12-31',
    ':user_id'    => 3
  ]);

  list ($totalMins, $remngSecs) = gmp_div_qr($qry->fetchColumn(), 60);
  list ($totalHour, $remngMins) = gmp_div_qr($totalMins, 60);

  echo "Worked a total of $totalHour:$remngMins:$remngSecs.";
?>

Have a look at timestampdiff which doesn't have the TIME limitation. I.e. something like (untested):

SELECT CONCAT(
        TIMESTAMPDIFF(HOURS, entry_end_time, entry_start_time), 
        ":",
        MOD(TIMESTAMPDIFF(MINUTES, entry_end_time, entry_start_time),60)
      )
AS total FROM entry 
WHERE entry_date BETWEEN '2012-01-01' AND '2012-12-31' AND user_id = 3

The concats not ideal, I'm sure there will be a more elegant solution.